The present invention relates generally to integrated circuits, and more particularly to standby regulator circuits.
As process dimensions for integrated circuits continue to shrink, the maximum operating voltages of the circuits may decrease correspondingly. It may be desirable to decrease operating voltages to prevent large electric fields from damaging circuit structures, such as gate oxide, diffusion depletion regions, and various insulating layers. However, in many applications, the integrated circuits are coupled to external systems having operating voltages that may not have decreased as rapidly. Therefore, integrated circuits manufactured in advanced semiconductor technologies may typically include voltage regulators which are supplied with high-level voltages. The voltage regulators may operate to output a lower voltage that is compatible with a maximum operating voltage of a supplied semiconductor technology.
In addition, it may be desirable in many applications to reduce system power, for example, to manage thermal and battery-powered operating budgets. Reducing system power may involve designing circuits to draw minimum amounts of current. Traditionally, average operating currents may be lowered by providing power-down modes. In a power-down mode, portions of a circuit are inactivated when not required to operate. However, even when portions of the circuit are inactivated, regulators supplying these circuits may typically continue operating and drawing current. For example, the voltage these regulators supply stays below the maximum allowable by the technology, but high enough to keep portions of the circuit alive and stable in a particular state (e.g., as a “keep-alive” function). By continuing to operate in a powered-down mode, these regulators may continue to draw substantial operating current, which may be inefficient.